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discover problems There are too many connections in the test environment. It is found that all the links are in the second rac node. No one calls or cares about the test environment Manually test the specified instance: C:\Users\caoyf>sqlplus system/xxxx@192.168.xxx.xxx:1521/server_taf SQL*Plus: Release 11.2.0.4.0 Producti ...

1. First look at the structure of the JVM runtime data area Thread exclusive: Each thread has its own space that is created and destroyed with the thread lifecycle. Thread sharing: All threads have access to this memory data, which is created and destroyed with the virtual machine GC. JVM stores loaded class information, constants, static var ...

Tools: eclipse jdk 1.8 oracle 11g ojdbc6.jar(Database driver package) Six steps of JDBC: Here we follow these six steps of jdbc: Registration driven Get connection Get execution sql statement object Execute sql statement Process result set close resource URL: Uniform Resource Locator oracle URL: jdbc:orac ...

1. Startup is the way to create bean s pom.xml <dependency> <groupId>com.alibaba</groupId> <artifactId>druid-spring-boot-starter</artifactId> <version>1.1.10</version> </dependency> <!-- maven Not in the warehouse oracle Database driver, here jar Put it under the project for i ...

1. The concept of reflection has been explained in the blog in the previous section. Next, we start to analyze the business requirements logic, and then use the reflection principle to realize it;2. Description: Usually, only one database can be connected to operate data in a project, but some complex businesses will u ...

order This paper mainly studies bootstrap check of elastic search BootstrapCheck elasticsearch-7.0.1/server/src/main/java/org/elasticsearch/bootstrap/BootstrapCheck.java public interface BootstrapCheck { /** * Encapsulate the result of a bootstrap check. */ final class BootstrapCheckResult { private final String mess ...

Reason: when using the spring datajpa statement to query the null value of a field in the database table, such as:findByIdAndNameIsNullfindByIdAndNameIsNotNullWhen the value of name is empty string, the result of query is very different 1. Build tables CREATE TABLE `user` ( `id` bigint(11) NOT NULL AUTO_INCREMENT, `name` varchar(45) CHARAC ...

When designing a table structure in a normal development system, it is often necessary to have a field to identify the uniqueness of the record, which is implemented from different dimensions of the java level and the database level java generates unique identity Version 1 Unique identifier UUID generated by java System.out.println(UUID.rando ...

  Configure repos source # cd /etc/yum.repos.d # wget http://yum.oracle.com/public-yum-ol7.repo The official website points out that the version to be installed is enable =1, so you need to modify the. repo file.   Download RMP-GPG-KEY wget http://public-yum.oracle.com/RPM-GPG-KEY-oracle-ol7 -O /etc/pki/rpm-gpg ...

encapsulation BaseDao What if the parameter, quantity and type are not fixed? public class TestMethod { //First, method overload /*public int sum(int a) { return a; } public int sum(int a,int b) { return a+b; } public int sum(int a,int b,int c) { return a+b+c; }*/ //Method 2, put an arra ...